Much earlier, people learned to mine iron. Just 450 years ago, the Spaniards landed in Central and South America, discovered rich cities there with huge public buildings, palaces and temples. However, it turned out that the Indians did not yet know iron. Their tools and weapons were made only of stone.
It is known from history that the peoples of Egypt, Mesopotamia and China 3-4 thousand years BC. e. produced gigantic construction works to harness the power of mighty rivers and direct the waters to the fields. All this work required many tools - picks, hoes, plows, and to protect against the attacks of nomads many weapons - swords and arrows. At the same time, not much copper and tin were mined. Therefore, the development of production required a new metal, more common in nature. The search for this metal was not easy: iron ores bear little resemblance to metal, and in ancient times it was, of course, difficult for a person to guess that they contained the metal he needed. In addition, in itself it is very soft; it is a poor material for making tools and weapons.
A lot of time passed before man learned to extract iron from ores and make iron from it.
It is possible that the first discoveries of iron as a material for the manufacture of various objects are associated with finds iron meteorites, consisting of native iron with an admixture of nickel. Perhaps, by watching meteorite iron rust, people realized that iron was contained in the yellow, earthy ochres often found on the surface of the earth, and then discovered ways to smelt iron.
According to historical data, approximately a thousand years BC. e. in Assyria, India, Urartu and some other countries they already knew how to mine and process iron. Tools and various weapons were made from it. In the 7th century BC e. The agricultural population living along the Dnieper and in the Black Sea steppes also knew how to mine iron. The Scythians used it to make knives, swords, arrowheads and spearheads, and other military and household items.
The mining and art of iron processing were widespread throughout Ancient Rus'.
Blacksmiths, popularly called “cunning” in those days, not only processed, but usually themselves extracted iron from ores. They were very respected. In folk tales, the blacksmith defeats the Serpent Gorynych, who personified evil forces, and performs many other heroic deeds.
Iron is a soft metal that can be easily forged, but in its pure form is unsuitable for making tools. Only alloys of iron with other substances give it the necessary properties, including hardness. Most important for National economy two alloys of iron and carbon - cast iron containing more than 2% (up to 6%) carbon, and steel, containing from 0.03 to 2% carbon.
In ancient times, people had no idea about cast iron, but they learned to make steel from iron. They smelted iron in primitive forges, mixing iron ore with charcoal. They obtained the high temperature necessary to smelt iron ore using ordinary bellows. They were set in motion by hand, and later by the power of water, installing water mills. After smelting the iron ore, a sintered mass of granular iron was obtained, which was then forged on anvils.
To make steel from iron, thin strips of forged iron were lined with charcoal and calcined along with the charcoal for several days. Of course, little steel was obtained this way, and it was expensive. The secrets of steel production were kept strictly. Was especially famous Damascus steel- damask steel, - the method of obtaining which was apparently developed by ancient Indian masters, and then mastered by Arab masters.
However, all these methods of processing iron ore and producing steel yielded little metal. The ever-increasing need for it forced people to look for new ways to obtain significantly large quantities metal At the end of the 14th - beginning of the 15th centuries, furnaces for smelting iron began to be built with a height of 2-3 m in order to obtain more metal. The craftsmen who carried out the melting in these furnaces noticed that some melts were unsuccessful. Instead of iron, a mass similar to iron was formed in the furnace, which, when cooled, gave a brittle, unforgeable substance. But, unlike iron and steel, this mass had remarkable property: it was obtained in a furnace in a molten state in the form of a liquid, it could be released through holes from the furnace and castings could be made from it different shapes. This was cast iron.
Of course, in the old days, metallurgists did not know how to explain why in some cases sintered malleable iron ended up in the furnace, and in others - liquid cast iron. Chemistry as a science did not exist in those days, and none of the craftsmen who made iron could know that the whole point was in the proportion between ore, coal and air entering the furnace during smelting. The more air (more precisely, oxygen) is supplied to the furnace, the more carbon will burn out and it will turn into carbon dioxide, which will evaporate, and little carbon will remain in the iron: this is how steel is obtained. If there is less air, then a lot of carbon dissolves in the iron: cast iron is formed.
Quite quickly, people learned to use cast iron not only for castings, but also for making malleable iron from it. To do this, a piece of cast iron was heated in forges and thereby burned off excess carbon from it.
Invention of the steam engine and the loom in the 18th century. and especially the construction railways V early XIX V. required a huge amount of metal. Once again, fundamental changes were needed in the production of iron and steel.
By 1784 in England, Cort introduced the processing of cast iron in so-called flame or reverberatory furnaces. This process is called puddling. In the reverberatory furnace they began to use it instead of wood. The use of coal in smelting was previously hindered by the sulfur that coal contains. It penetrated into the iron when it came into contact with coal. And the sulfur-containing iron became brittle as soon as it was heated.
In a reverberatory furnace, the firebox is separated by a threshold from the bath where the cast iron is melted, and thus the coal does not come into direct contact with. Cast iron is heated by a flame and hot air passing over it from the firebox and reflected from the roof of the furnace. Along with the improvement of the method of producing cast iron, an intensified search was carried out for new methods of producing steel.
The secret of preparing Damascus steel - damask steel - was discovered by the famous Russian metallurgist Pavel Petrovich Anosov, who worked at the Zlatoust Metallurgical Plant in the first half of the 19th century. He alloyed iron with graphite, which is also carbon, in small crucibles to create the remarkable Damascus steel. The cliche made of this steel was stronger than the strongest English steel, which at that time was considered the best in the world.
In 1856, the English engineer Bessemer proposed blowing air into the “nozzles” - holes in the bottom of the retort - through molten cast iron, due to which in 10-20 minutes all excess coal was converted into carbon dioxide, and cast iron into steel.
Later, a method of melting steel in reverberatory furnaces, called open hearth. Open hearth reverberatory furnaces are much better than the old reverberatory furnaces. In special devices of open-hearth furnaces - regenerators - air and combustible gas obtained from coal are preheated to 1000°. Heating occurs due to heat flue gases coming from the same oven. Heating the gas and air contributes to the development (during gas combustion) of a temperature of about 1800°. This is enough to melt cast iron and scrap steel.
Particularly high-quality steel is now smelted in electric furnaces, where the metal is produced by melting in a voltaic arc, the temperature of which reaches 3000°. The advantages of electric smelting are that the metal is not contaminated with harmful impurities that are always present in the fuel gases burned in conventional furnaces.
Cast iron is smelted in blast furnaces. The height of a modern blast furnace together with auxiliary devices is 40 meters or more. To lower the melting point of iron ore, add flux, or deer, - a substance that, when combined with some components ore, forms a low-melting slag. Typically, fluorspar, or fluorite, etc. are used as flux. The mixture of ore and flux is called charge. The charge is poured into another furnace mixed with coke, which, when burned, heats and melts the entire mixture. Coke burns normally only if air is blown into it, preheated to 600-850°. The air is heated by gases coming from the blast furnace in steel towers - kauiorax- lined with bricks inside.
At the very bottom of the furnace, the hot air meets with hot air and burns. This produces carbon dioxide (CO2). As it rises, it turns into another gas - carbon monoxide (CO), which is characterized by high chemical activity.
Carbon monoxide greedily takes oxygen away from iron oxides. In this way, metallic iron containing carbon is released, i.e. cast iron, which then flows into the bottom of the blast furnace. From time to time it is released through a special hole in the oven, and it flows into the molds, where it cools.
The iron ore industry is a branch of the iron and steel industry that mines and processes iron ore to turn it into iron and steel. Since iron is a fairly common element, it is obtained only from those rocks, in which there is more of it.
Humanity learned to mine and process this mineral formation later than anything else, apparently because iron ore bears little resemblance to metal. Now it’s hard to imagine without iron and steel modern world: the transport, construction industry, agriculture and many other areas cannot do without metal. About how and what iron ore turns into in a simple process chemical processes, will be discussed further.
Iron ore varies in the amount of iron it contains. It can be rich, in which it is more than 57%, and poor - from 26%. Low-grade ores are used in industry only after they have been enriched.
By origin, ore is divided into:
Iron ores are also divided into:
The answer to the main question of the article “iron ore: what is made from it” is very simple: steel, cast iron, steel cast iron and iron are extracted from iron ore.
In this case, metallurgical production begins with the extraction of the main components for the production of metals: coal, iron ore, fluxes. Then, at mining and processing plants, the extracted iron ore is enriched, getting rid of waste rocks. Special plants prepare coking coal. In blast furnaces, ore is converted into pig iron, which is then used to produce steel. And steel, in turn, turns into a finished product: pipes, sheet steel, rolled products, etc.
The production of ferrous metals is conventionally divided into two stages, in the first of which cast iron is produced, in the second cast iron is converted into steel.
Cast iron is an alloy of carbon and iron, which also includes manganese, sulfur, silicon, and phosphorus.
Pig iron is produced in blast furnaces, in which iron ore is reduced from iron oxides at high temperatures, separating out the waste rock. Fluxes are used to reduce the melting point of waste rock. Ore, fluxes and coke are loaded into the blast furnace in layers.
Heated air is supplied to the lower part of the furnace to support combustion. This is how a series of chemical processes occur, resulting in molten iron and slag.
The resulting cast iron comes in different types:
Almost 90% of all mined cast iron is pig iron, that is, it is used in the production of steel, which is produced in open-hearth or electric furnaces, in convectors. At the same time, new methods for producing steel are emerging:
In steel, when compared with cast iron, there is less silicon, phosphorus and sulfur, that is, when producing steel, it is necessary to reduce their amount using oxidative smelting produced in open-hearth furnaces.
Open hearth is a furnace in which gas is burned above the melting space, creating required temperature from 1700 to 1800°C. Deoxidation is carried out using ferromanganese and ferrosilicon, then final stage- using ferrosilicon and aluminum in a steel-pouring ladle.
Higher quality steel is produced in induction and electric arc furnaces, in which the temperature is higher, so the output is refractory steel. At the first stage of steel production, an oxidative process occurs with the help of air, oxygen and charge oxide, at the second - a reduction process, which consists in deoxidation of steel and removal of sulfur.
To summarize the topic "iron ore: what is made from it", we need to list the four main products of ferrous metallurgy:
Iron is an element of the side subgroup of the eighth group of the fourth period of the periodic table of chemical elements with atomic number 26. It is designated by the symbol Fe (lat. Ferrum). One of the most common in earth's crust metals (second place after aluminum).
The simple substance iron (CAS number: 7439-89-6) is a malleable silver-white metal with high chemical reactivity: iron quickly corrodes when high temperatures or when high humidity on air. Iron burns in pure oxygen, and in a finely dispersed state it spontaneously ignites in air.
In fact, iron is usually called its alloys with a low impurity content (up to 0.8%), which retain the softness and ductility of the pure metal. But in practice, alloys of iron with carbon are more often used: steel (up to 2.14 wt.% carbon) and cast iron (more than 2.14 wt.% carbon), as well as stainless (alloy) steel with additions of alloying metals (chrome, manganese, nickel, etc.). Totality specific properties iron and its alloys make it the “No. 1 metal” in importance for humans.
In nature, iron is rarely found in its pure form; most often it is found in iron-nickel meteorites. The abundance of iron in the earth's crust is 4.65% (4th place after O, Si, Al). Iron is also believed to make up most of the earth's core.
There are several versions of the origin of the Slavic word “iron” (Belarusian zheleza, Ukrainian zalizo, Old Slavic zhelezo, Bulgarian zhelezo, Serbo-Croatian zhejezo, Polish żelazo, Czech železo, Slovenian železo).
One of the etymologies connects Praslav. *želězo with the Greek word χαλκός, which meant iron and copper, according to another version *želězo is cognate with the words *žely “turtle” and *glazъ “rock”, with a common seme “stone”. The third version suggests an ancient borrowing from an unknown language.
Romance languages (Italian ferro, French fer, Spanish hierro, Port ferro, Roman fier) continue Lat. ferrum. Latin ferrum (Germanic languages borrowed the name of iron (Gothic eisarn, English iron, German Eisen, Dutch ijzer, Danish jern, Swedish järn) from Celtic.
The Proto-Celtic word *isarno- (> Old Irish iarn, Old Brett hoiarn) probably goes back to Proto-I.E. *h1esh2r-no- “bloody” with the semantic development “bloody” > “red” > “iron”. According to another hypothesis given word goes back to pra-i.e. *(H)ish2ro- “strong, holy, possessing supernatural power.”
The ancient Greek word σίδηρος may have been borrowed from the same source as the Slavic, Germanic and Baltic words for silver.
The name of natural iron carbonate (siderite) comes from the Latin. sidereus - starry; Indeed, the first iron that fell into the hands of people was of meteorite origin. Perhaps this coincidence is not accidental. In particular, the ancient Greek word sideros (σίδηρος) for iron and the Latin sidus, meaning "star", probably have a common origin.
In industry, iron is obtained from iron ore, mainly from hematite (Fe 2 O 3) and magnetite (FeO Fe 2 O 3).
Exist various ways extraction of iron from ores. The most common is the domain process.
The first stage of production is the reduction of iron with carbon in blast furnace at a temperature of 2000 °C. In a blast furnace, carbon in the form of coke, iron ore in the form of agglomerate or pellets, and flux (such as limestone) are fed from above, and are met by a stream of forced hot air from below.
In the furnace, carbon in the form of coke is oxidized to carbon monoxide. This oxide is formed during combustion in a lack of oxygen. In turn, carbon monoxide reduces iron from the ore. To make this reaction go faster, heated carbon monoxide passed through iron(III) oxide. Flux is added to get rid of unwanted impurities (primarily silicates; such as quartz) in the mined ore. A typical flux contains limestone (calcium carbonate) and dolomite (magnesium carbonate). To remove other impurities, other fluxes are used.
The action of flux (in in this case calcium carbonate) is that when it is heated it decomposes to its oxide. Calcium oxide combines with silicon dioxide to form slag - calcium metasilicate. Slag, unlike silicon dioxide, is melted in a furnace. Slag, lighter than iron, floats on the surface - this property allows the slag to be separated from the metal. The slag can then be used in construction and agriculture. The molten iron produced in a blast furnace contains quite a lot of carbon (cast iron). Except in cases where cast iron is used directly, it requires further processing.
Excess carbon and other impurities (sulfur, phosphorus) are removed from cast iron by oxidation in open-hearth furnaces or converters. Electric ovens They are also used for smelting alloy steels.
In addition to the blast furnace process, the process of direct iron production is common. In this case, pre-crushed ore is mixed with special clay, forming pellets. The pellets are fired and treated in a shaft furnace with hot methane conversion products, which contain hydrogen. Hydrogen easily reduces iron without contaminating the iron with impurities such as sulfur and phosphorus, which are common impurities in coal. Iron is obtained in solid form, and is subsequently melted in electric furnaces.
Chemically pure iron is obtained by electrolysis of solutions of its salts.
Iron makes up more than 5% of the earth's crust. The main ores used to extract iron are hematite and magnetite. These ores contain from 20 to 70% iron. The most important iron impurities in these ores are sand and alumina (aluminum oxide).
Based on indirect evidence, we can conclude that the Earth's core is mainly an iron alloy. Its radius is approximately 3470 km, while the radius of the Earth is 6370 km. The Earth's inner core appears to be solid and has a radius of about 1,200 km. It is surrounded by a liquid outer core. The turbulent flow of fluid in this part of the core creates the Earth's magnetic field. The pressure inside the core ranges from 1.3 to 3.5 million atmospheres, and the temperature ranges from
Although it is established that the Earth's core is composed mostly of iron, its exact composition is unknown. It is estimated that 8 to 10% of the mass of the earth's core is made up of elements such as nickel, sulfur (in the form of iron sulfide), oxygen (in the form of iron oxide) and silicon (in the form of iron silicide).
At least 12 countries in the world have proven iron ore reserves that exceed a billion tons. These countries include Australia, Canada, USA, South Africa, India, USSR and France. The global level of steel production currently reaches 700 million tons. The main producers of steel are the USSR, the USA, and Japan; each of these countries produces more than 100 million tons of steel per year. In Great Britain, the level of steel production is 20 million tons per year.
The extraction of iron from iron ore is carried out in two stages. It begins with preparing the ore—grinding and heating. The ore is crushed into pieces with a diameter of no more than 10 cm. The crushed ore is then calcined to remove water and volatile impurities.
In the second stage, iron ore is reduced to iron using carbon monoxide in a blast furnace (Fig. 14.12). Reduction is carried out at temperatures of about 700°C:
To increase the yield of iron, this process is carried out under conditions of excess carbon dioxide
Carbon monoxide CO is formed in a blast furnace from coke and air. The air is first heated to approximately 600 °C and forced into the furnace through a special pipe - a tuyere. The coke burns in hot compressed air to form carbon dioxide. This reaction is exothermic and causes a temperature increase above 1700 °C:
Carbon dioxide rises up in the furnace and reacts with more coke to form carbon monoxide. This reaction is endothermic:
Rice. 14.12. Blast furnace, 1 - iron ore, limestone, coke, 2 loading cone (top), 3 - top gas, 4 - furnace masonry, 5 - iron oxide reduction zone, 6 - slag formation zone, 7 - coke combustion zone, 8 - injection of heated air through tuyeres, 9 - molten iron, 10 - molten slag.
The iron formed during the reduction of ore is contaminated with impurities of sand and alumina (see above). To remove them, limestone is added to the kiln. At the temperatures existing in the kiln, limestone undergoes thermal decomposition with the formation of calcium oxide and carbon dioxide:
Calcium oxide combines with impurities to form slag. The slag contains calcium silicate and calcium aluminate:
Iron melts at 1540°C (see Table 14.2). The molten iron along with the molten slag flows into the lower part of the furnace. Molten slag floats on the surface of molten iron. Each of these layers is periodically released from the oven at the appropriate level.
The blast furnace operates around the clock, in continuous mode. The raw materials for the blast furnace process are iron ore, coke and limestone. They are constantly fed into the oven through top part. Iron is released from the furnace four times a day, at regular intervals. It pours out of the furnace in a fiery stream at a temperature of about 1500 °C. Blast furnaces are different sizes and productivity (1000-3000 tons per day). In the USA there are some new oven designs with
four outlets and continuous release of molten iron. Such furnaces have a capacity of up to 10,000 tons per day.
Iron smelted in a blast furnace is poured into sand molds. This kind of iron is called cast iron. The iron content in cast iron is about 95%. Cast iron is a hard but brittle substance with a melting point of about 1200 °C.
Cast iron is made by fusing a mixture of pig iron, scrap metal and steel with coke. Molten iron is poured into molds and cooled.
Wrought iron is the most pure form technical hardware. It is produced by heating crude iron with hematite and limestone in a smelting furnace. This increases the purity of iron to approximately 99.5%. Its melting point rises to 1400 °C. Wrought iron has great strength, malleability and ductility. However, for many applications it is replaced by mild steel (see below).
Steels are divided into two types. Carbon steels contain up to 1.5% carbon. Alloy steels contain not only small amounts of carbon, but also specially introduced impurities (additives) of other metals. Below are discussed in detail Various types steels, their properties and applications.
Oxygen converter process. In recent decades, steel production has been revolutionized by the development of the basic oxygen process (also known as the Linz-Donawitz process). This process began to be used in 1953 in steelworks in two Austrian metallurgical centers - Linz and Donawitz.
The oxygen converter process uses an oxygen converter with a main lining (lining) (Fig. 14.13). The converter is loaded in an inclined position
Rice. 14.13. Converter for steel smelting, 1 - oxygen and 2 - water-cooled tube for oxygen blast, 3 - slag. 4-axis, 5-molten steel, 6-steel body.
molten pig iron from the smelting furnace and scrap metal, then returned to a vertical position. After this, the converter is injected from above copper tube with water cooling and through it a stream of oxygen mixed with powdered lime is directed onto the surface of the molten iron. This “oxygen purge”, which lasts 20 minutes, leads to intense oxidation of iron impurities, and the contents of the converter remain liquid due to the release of energy during the oxidation reaction. The resulting oxides combine with lime and turn into slag. The copper tube is then pulled out and the converter is tilted to drain the slag. After repeated blowing, the molten steel is poured from the converter (in an inclined position) into a ladle.
The oxygen-converter process is used primarily to produce carbon steels. It is characterized by high productivity. In 40-45 minutes, 300-350 tons of steel can be produced in one converter.
Currently, all steel in the UK and most steel worldwide is produced using this process.
Electric steelmaking process. Electric furnaces are mainly used for converting scrap steel and cast iron into high quality alloy steels, e.g. stainless steel. The electric furnace is a round deep tank lined with refractory bricks. The furnace is loaded with scrap metal through the open lid, then the lid is closed and electrodes are lowered into the furnace through the holes in it until they come into contact with the scrap metal. After this, the current is turned on. An arc occurs between the electrodes, in which a temperature above 3000 °C develops. At this temperature, the metal melts and new steel is formed. Each furnace load allows you to produce 25-50 tons of steel.
Known to mankind was of cosmic origin, or, more precisely, meteorite. It began to be used as an instrumental material approximately 4 thousand years BC. The technology of metal smelting appeared several times and was lost as a result of wars and unrest, but, according to historians, the Hittites were the first to master smelting.
It is worth noting that we're talking about about iron alloys a small amount impurities. It became possible to obtain chemically pure metal only with the advent of modern technologies. This article will tell you in detail about the features of metal production by direct reduction, flash, sponge, raw material, hot briquetted iron, and we will touch on the production of chlorine and pure substances.
First, it’s worth considering the method of producing iron from iron ore. Iron is a very common element. In terms of content in the earth's crust, the metal ranks 4th among all elements and 2nd among metals. In the lithosphere, iron is usually presented in the form of silicates. Its highest content is observed in basic and ultrabasic rocks.
Almost all mining ores contain some amount of iron. However, only those rocks in which the proportion of the element is of industrial importance are developed. But even in this case, the amount of minerals suitable for development is more than large.
Mineral rocks are classified according to their iron content as follows:
The general technological cycle of iron production in the form of cast iron, steel and rolled products is discussed in this video:
There are several methods for extracting ore. The one that is found most economically feasible is used.
All metals and alloys are divided into non-ferrous (like, etc.) and ferrous. The latter include cast iron and steel. 95% of all metallurgical processes occur in ferrous metallurgy.
Despite the incredible variety of steels produced, there are not so many manufacturing technologies. In addition, cast iron and steel are not exactly 2 different products; cast iron is a mandatory preliminary stage in the production of steel.
Both cast iron and steel are classified as iron alloys, where the alloying component is carbon. Its share is small, but it gives the metal very high hardness and some brittleness. Cast iron, because it contains more carbon, is more brittle than steel. Less plastic, but has better heat capacity and resistance to internal pressure.
Cast iron is produced by blast furnace smelting. There are 3 types:
Steel can contain no more than 2% carbon; it is produced in 3 main ways. But in any case, the essence of steelmaking comes down to annealing unwanted impurities of silicon, manganese, sulfur, and so on. In addition, if alloy steel is produced, additional ingredients are introduced during the manufacturing process.
According to their intended purpose, steel is divided into 4 groups:
Even rich ore must be prepared before smelting iron - freed from waste rock.
This video will tell you in detail about the production of iron:
Pig iron is smelted from ore in a blast furnace:
The resulting cast iron is transported in ladles to a steelmaking shop or to a casting machine, where cast iron ingots are produced.
Turning cast iron into steel is done in 3 ways. During the smelting process, excess carbon and unwanted impurities are burned off, and necessary components are also added - when welding special steels, for example.
Since 1970, the method of direct reduction of iron has also been used. The method allows you to bypass the costly stage of producing cast iron in the presence of coke. The first installations of this kind were not very productive, but today the method has become quite well known: it turned out that natural gas can be used as a reducing agent.
The raw materials for recovery are pellets. They are loaded into a shaft furnace, heated and purged with a gas conversion product - carbon monoxide, ammonia, but mainly hydrogen.
The reaction occurs at a temperature of 1000 C, with hydrogen reducing iron from the oxide.
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The largest share of iron ore deposits is in Russia and Brazil – 18%, Australia – 14%, and Ukraine – 11%. The largest exporters are Australia, Brazil and India. The peak price of iron was observed in 2011, when a ton of metal was estimated at $180. By 2016 the price had dropped to $35 per ton.
The prevalence of iron is great, the extraction method is quite simple, and ultimately smelting is an economically profitable process. Together with physical characteristics production and provides iron with the role of the main structural material.
The production of ferric chloride is shown in this video:
